Bullying among females, once thought to be relatively rare, has been recently recognized as an extremely serious problem. Young girls who are aggressive towards others experience a host of externalizing, internalizing, and social difficulties. This application describes a project to study girls' peer entry bids and social cognitions in a free-play environment as a strategy for learning how to intervene with at-risk young girls. Further, peer entry bids of young aggressive girls are especially important to investigate given research documenting that young females base friendships on and greatly value companionship, intimacy, and inclusion, all of which are emphasized when a girl attempts to join an existing group of peers. In the proposed study, 3rd and 4th grade females attending six public elementary schools in an urban, culturally diverse, disadvantaged area of Philadelphia, would be eligible to participate. The Principal Investigator has designed an innovative video methodology to examine the behavior and social-cognitive processing of two subgroups of inner-city aggressive girls and a control group of non-aggressive girls. Results from the peer entry portion of the study would be used to test the efficacy of a social skills/social-cognitive group intervention for aggressive girls that would be compared to a standard treatment. The Principal Investigator notes that this project would be the first to design a school-based intervention project for relationally aggressive girls (girls who display their aggression by manipulating relationships through gossiping, leaving others out, or ignoring others).